ETSI TS 138 401 V17.3.0 (2023-01)

5G; NG-RAN; Architecture description (3GPP TS 38.401 version 17.3.0 Release 17)

RTS/TSGR-0338401vh30

General Information

• Status: Not Published
• Technical Committee: 3GPP RAN 3 - lub specification, lur specification, lu specification and UTRAN & O&M
• Current Stage: 12 - Citation in the OJ (auto-insert)
• Completion Date: 17-Jan-2023

Standards Content (Sample)

ETSI TS 138 401 V17.3.0 (2023-01)






TECHNICAL SPECIFICATION
5G;
NG-RAN;
Architecture description
(3GPP TS 38.401 version 17.3.0 Release 17)

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3GPP TS 38.401 version 17.3.0 Release 17 1 ETSI TS 138 401 V17.3.0 (2023-01)

Reference
RTS/TSGR-0338401vh30
Keywords
5G
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ETSI

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3GPP TS 38.401 version 17.3.0 Release 17 2 ETSI TS 138 401 V17.3.0 (2023-01)
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ETSI

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3GPP TS 38.401 version 17.3.0 Release 17 3 ETSI TS 138 401 V17.3.0 (2023-01)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 7
1 Scope . 8
2 References . 8
3 Definitions and abbreviations . 9
3.1 Definitions . 9
3.2 Abbreviations . 11
4 General principles . 12
5 General architecture . 12
5.1 General . 12
5.2 User plane . 13
5.3 Control plane . 13
6 NG-RAN architecture. 14
6.1 Overview . 14
6.1.1 Overall Architecture of NG-RAN . 14
6.1.2 Overall architecture for separation of gNB-CU-CP and gNB-CU-UP . 15
6.1.3 Overall Architecture of IAB . 16
6.1.4 Protocol stacks of IAB . 17
6.1.5 Overall Architecture of NR MBS . 19
6.1.6 Protocol stacks of L2 UE-to-Network Relay . 19
6.2 NG-RAN identifiers . 20
6.2.1 Principle of handling Application Protocol Identities . 20
6.2.2 gNB-DU ID . 22
6.2.3 ng-eNB-DU ID . 22
6.2.4 gNB-CU-UP ID . 23
6.3 Transport addresses . 23
6.4 UE associations in NG-RAN Node . 23
6.5 MBS Session associations in NG-RAN Node . 24
7 NG-RAN functions description . . 25
7.0 General . 25
7.1 NG-RAN sharing . 25
7.2 Remote Interference Management . 26
7.3 Cross-Link Interference Management . 26
7.4 Support for Non-Public Networks . 26
7.5 RACH Optimisation Function . 26
7.6 Positioning . 26
7.7 Support for NR MBS . 26
7.7.1 Support of dynamic PTP and PTM switching. 26
7.8 PCI Optimisation Function . 27
7.9 Support for CCO . 27
7.9.1 General . 27
7.9.2 OAM requirements . 27
7.9.3 Dynamic coverage configuration changes . 27
7.10 Support of RAN visible QoE measurement. 27
8 Overall procedures in gNB-CU/gNB-DU Architecture . 27
8.1 UE Initial Access . 27
8.2 Intra-gNB-CU Mobility . 29
8.2.1 Intra-NR Mobility . 29
8.2.1.1 Inter-gNB-DU Mobility . 29
ETSI

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3GPP TS 38.401 version 17.3.0 Release 17 4 ETSI TS 138 401 V17.3.0 (2023-01)
8.2.1.2 Intra-gNB-DU handover . 30
8.2.1.3 Inter-gNB-DU Conditional Handover or Conditional PSCell Change . 31
8.2.2 EN-DC Mobility . 32
8.2.2.1 Inter-gNB-DU Mobility using MCG SRB . 32
8.2.2.2 Inter-gNB-DU Mobility using SCG SRB (SRB3) . 34
8.2.2.3 Inter-gNB-DU Conditional PSCell Change using MCG SRB without MN negotiation . 34
8.2.3 Intra-CU topology adaptation procedure . 36
8.2.3.1 Intra-CU topology adaptation procedure in SA. 36
8.2.3.2 Intra-CU topology adaptation procedure in NSA using MCG SRB. 39
8.2.3.3 Intra-CU topology adaptation procedure in NSA using SCG SRB (SRB3) . 41
8.2.4 Intra-CU topological redundancy procedure . 41
8.2.5 Intra-CU Backhaul RLF recovery for IAB-nodes in SA mode . 44
8.3 Mechanism of centralized retransmission of lost PDUs . 45
8.3.1 Centralized Retransmission in Intra gNB-CU Cases . 45
8.4 Multi-Connectivity operation . 46
8.4.1 Secondary Node Addition . 46
8.4.1.1 EN-DC . 46
8.4.2 Secondary Node Release (MN/SN initiated) . 47
8.4.2.1 EN-DC . 47
8.4.3 SCG suspend/resume in RRC_INACTIVE . 48
8.4.4 SCG Deactivation and Activation . 49
8.4.4.1 SN Addition with SCG Activation or Deactivation . 50
8.4.4.2 MN initiated SN Modification with SCG Activation or Deactivation . 51
8.4.4.3 SN initiated SN Modification with SCG Activation or Deactivation . 52
8.5 F1 Startup and cells activation . 52
8.6 RRC state transition. 54
8.6.1 RRC connected to RRC inactive. 54
8.6.2 RRC inactive to other states . 54
8.7 RRC connection reestablishment . 56
8.8 Multiple TNLAs for F1-C . 58
8.9 Overall procedures involving E1 and F1 . 59
8.9.1 UE Initial Access . 59
8.9.2 Bearer context setup over F1-U . 60
8.9.3 Bearer context release over F1-U . 61
8.9.3.1 gNB-CU-CP initiated bearer context release . 61
8.9.3.2 gNB-CU-UP initiated bearer context release . 62
8.9.4 Inter-gNB handover involving gNB-CU-UP change . 63
8.9.5 Change of gNB-CU-UP . 65
8.9.6 RRC State transition . 66
8.9.6.1 RRC Connected to RRC Inactive . 66
8.9.6.2 RRC Inactive to other states . 67
8.9.7 Trace activation/deactivation over F1 and E1 . 69
8.9.8 BH RLC channel establishment procedure . 69
8.9.9 Traffic Mapping . 71
8.9.9.1 Traffic Mapping from IP-layer to Layer-2 . 71
8.9.9.2 BH RLC Channel Mapping on BAP Layer . 71
8.9.10 IAB-node release . 71
8.9.10.1 IAB-node orderly release . 72
8.9.10.2 IAB-node disorderly release. 72
8.9.11 IAB-node OAM . 72
8.9.12 Handling of IAB-MTs in INACTIVE State . 72
8.9.13 IP Address Allocation for IAB-nodes . 72
8.10 Multiple TNLAs for E1 . 73
8.11 Support of Network Sharing with multiple cell-ID broadcast . 75
8.11.1 General . 75
8.11.2 Initial Registration – separate PLMN signalling . 75
8.11.3 RRC Connection Reestablishment – separate PLMN signalling . 76
8.11.4 Support of shared signalling transport . 77
8.12 IAB-node Integration Procedure . 77
8.12.1 Standalone IAB integration . 77
8.12.2 NSA IAB Integration procedure . 78
8.13 Overall procedures for MDT . 80
ETSI

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3GPP TS 38.401 version 17.3.0 Release 17 5 ETSI TS 138 401 V17.3.0 (2023-01)
8.13.0 General . 80
8.13.1 Signalling based MDT activation . 80
8.13.2 Management based MDT activation . 80
8.13.2.1 General . 80
8.13.2.2 Management based MDT Activation in gNB-CU-CP . 81
8.13.2.3 Management based MDT Activation in gNB-DU . 81
8.13.2.4 Management based MDT Activation in gNB-CU-UP . 82
8.13.2.5 User consent propagation in EN-DC . 83
8.13.2.6 User consent propagation in MR-DC with 5GC . 84
8.13.2.7 Management based trace activation in MR-DC with 5GC . 85
8.13.3 Alignment of MDT and QoE Measurements . 86
8.13.4 MDT reporting . 86
8.14 Self-optimisation . 86
8.14.1 Overall procedures for MRO . 86
8.14.1.1 Signalling of RLF information from gNB-CU to gNB-DU . 87
8.14.1.2 Signalling of RACH information from gNB-CU to gNB-DU . 87
8.15 Overall procedures for NR MBS . 88
8.15.1 General . 88
8.15.1.1 Broadcast MBS Session Setup . 88
8.15.1.2 Multicast MBS Session Context Establishment . 89
8.15.1.3 Multicast MRB type re-configuration with F1-U ptp-retransmission tunnel establishment . 91
8.15.2 Mobility procedure for Multicast . 92
8.15.2.1 Inter-gNB-CU Mobility between MBS Supporting nodes . 92
8.16 Overall procedures for CPAC . 93
8.16.1 MN initiated Conditional PSCell Addition . 93
8.16.2 MN initiated conditional SN Change . 94
8.16.3 SN initiated conditional inter-SN Change . 94
8.17 IAB Inter-CU Topology Management . 94
8.17.1 IAB Inter-donor-DU Re-routing . 94
8.17.2 IAB Inter-CU Topology Redundancy . 95
8.17.2.1 IAB Inter-CU topological redundancy procedure . 95
8.17.3 IAB Inter-CU Topology Adaptation . 98
8.17.3.1 IAB inter-CU topology adaptation procedure . 98
8.17.3.2 IAB inter-CU topology adaptation procedure with descendant IAB-node. 101
8.17.4 IAB Inter-CU Backhaul RLF recovery for single connected IAB-node . 103
8.18 Overall procedure for Small Data Transmission during RRC Inactive . 106
8.18.1 RACH based SDT . 106
8.18.2 CG based SDT . 107
8.18.3 RA-SDT or non-SDT with CG-SDT configuration .
...